A semiconductor light emitting device comprises a metallic support plate 1; a light-reflective reflector 3 mounted on the support plate 1 and formed with a hole 3a; a semiconductor light emitting element 2 mounted on the support plate 1 within the hole 3a of the reflector 3, and a plastic encapsulant 6 for sealing an outer periphery of the reflector 3 and an upper surface 1c of the support plate 1. As the reflector 3 is electrically connected to a wiring conductor 5 or a lead wire 8 extends through a notch 3k formed in the reflector 3 to electrically connect the semiconductor light emitting element 2 and wiring conductor 5, wiring span of the lead wire 8 can be shortened to prevent deformation of the lead wire 8. Simultaneously, diameter of the reflective surface 3c in the reflector 3 is reduced and height of the reflector 3 is increased to improve directivity and axial brightness of light from the semiconductor light emitting device. Also, formation of the hole 3a effectively prevents further thermal degradation of heat-resistible plastic encapsulant 6 or other resin components.